1. Field of the Invention
The invention relates to test tubes used in the microbiological field. More specifically, the invention is a test tube having a smaller test tube inverted and fused to the bottom (hereafter referred to as Lee's Tube). This design permits a layer of agar medium to solidify around the inside edge of the outer tube with a minimal incorporation of oxygen. At the same time, a black wooden or plastic rod may be inserted into the smaller tube to provide a dark background for easier counting. On the other hand, a permanently dark colored inner tube can be inverted and fused to the bottom of the outer tube. This will create the same dark-background effect without inserting a colored rod.
A rubber stopper or screw cap can be used for closing the tube. In this system, anaerobic, or facultatively anaerobic microorganisms will grow well while the ordinary petri plate fails to provide the same results. The tube saves space in the incubator and can even be incubated in a water bath for faster cultivation of test organisms. It is also suitable to carry in the field where petri plates give difficulties in handling.
2. Description of the Prior Art
The methods of cultivation or enumeration of a given microbiological sample are rather unique. The most popular method presently used is the petri plate. The petri plate consists of a bottom and a cover. The sample is properly diluted and delivered to the bottom of the dish. Molten agar is then added and allowed to solidify. Since the structure of the petri plate is as such, a large amount of oxygen is incorporated into the medium during processing of the sample, causing the inhibition of anaerobic or facultatively anaerobic microorganisms. To overcome this problem, the petri plate is simply incubated in an incubator containing CO.sub.2, N.sub.2, H.sub.2 or combinations of these gases. But this is an expensive, time-consuming operation which needs special equipment with a well-trained technician. The other technique for the cultivation of anaerobic bacteria employs the use of a pre-reduced medium in an ordinary test tube. In this method, a pre-reduced medium in a tube with a rubber stopper is autoclaved and cooled in a water bath. The test sample is then inoculated under the CO.sub.2 or N.sub.2 stream followed by spinning the tube horizontally. After the agar and the sample mixture have been solidified, the tube is incubated. Here again, the procedure is complicated, time-consuming, and requires the services of a highly trained microbiologist.
Even after the anaerobes have grown in the tube, it is very difficult to enumerate the developed colonies because the colonies on the other side of the agar surface are visible through the transparent glass tube.
The present invention allows one to overcome all these problems. The method of cultivating microorganisms is as simple as in the petri plate method and yet it provides a complete blockage of the view of the other side of the tube. Therefore, counting is as easy as in the petri plate method. Strict anaerobes can be grown by employing the rubber stopper and a proper anaerobic technique.